According to this rule, the age of the younger person should not be less than half the age of the older person plus seven years, so that (for example) no one older than 65 should be in a relationship with anyone younger than 39 and a half, no one older than 22 should be in a relationship with anyone younger than 18,

What is the rule on age difference in dating?

This rule states that by dividing your own age by two and then adding seven you can find the socially acceptable minimum age of anyone you want to date. So if youre a 24-year-old, you can feel free to be with anyone who is at least 19 (12 + 7) but not someone who is 18.